Copper alloy having excellent stress relaxation property

Abstract

A Cu—Ni—Sn—P alloy is provided, which is excellent in stress relaxation property in a direction perpendicular to a rolling direction, and has any of high strength, high conductivity, and excellent bendability. A copper alloy contains 0.1 to 3.0% of Ni, 0.1 to 3.0% of Sn, and 0.01 to 0.3% of P in mass percent respectively, and includes copper and inevitable impurities as the remainder; wherein in a radial distribution function around a Ni atom according to a XAFS analysis method, a first peak position is within a range of 2.16 to 2.35 Å, the position indicating a distance between a Ni atom in Cu and an atom nearest to the Ni atom. Thus, distances to atoms around the Ni atom in Cu are comparatively increased, so that the stress relaxation property in a direction perpendicular to the rolling direction of the copper alloy is improved.

What is claimed is: 
     
       1. A copper alloy having excellent stress relaxation properties comprising:
 0.1 to 3.0% of Ni, 
 0.1 to 3.0% of Sn, and 
 0.01 to 0.3% of P, 
 
       in mass percent respectively, and the remainder being copper and inevitable impurities,
 wherein the Ni/P ratio in the copper alloy is from 10.2 to 17.5; 
 wherein in a radial distribution function around a Ni atom according to a XAFS analysis method, a first peak position is within a range of 2.16 to 2.35 Å, the position indicating a distance between a Ni atom in Cu and an atom nearest to the Ni atom; 
 wherein said copper alloy has a conductivity of 24 to 41% IACS; 
 wherein said excellent stress relaxation properties are defined as having a stress relaxation ratio of 10 to 15% in the direction perpendicular to the direction the copper alloy is rolled; and 
 wherein said copper alloy is made by a method which comprises:
 (1) final cold rolling wherein the range of the draft in final cold rolling is 30 to 70%; and 
 (2) low-temperature annealing in a continuous annealing furnace at a substance temperature of 300 to 500° C. after final cold rolling, with a heating rate of low-temperature annealing in the continuous annealing furnace of 50° C./sec or more and a cooling rate after low-temperature annealing in the continuous annealing furnace of 100° C./sec or more. 
 
 
     
     
       2. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy further comprises 0.5% or less of Fe, 1% or less of Zn, 0.1% or less of Mn, 0.1% or less of Si, and 0.3% or less of Mg in mass percent. 
     
     
       3. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy further comprises at least one element selected from the group consisting of Ca, Zr, Ag, Cr, Cd, Be, Ti, Co, Au and Pt, and a total content of the element is 1.0% or less in mass percent. 
     
     
       4. The copper alloy having excellent stress relaxation properties according to  claim 2 , wherein the copper alloy further comprises at least one element selected from the group consisting of Ca, Zr, Ag, Cr, Cd, Be, Ti, Co, Au and Pt, and a total content of the element is 1.0% or less in mass percent. 
     
     
       5. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy further comprises at least one element selected from the group consisting of Hf, Th, Li, Na, K, Sr, Pd, W, S, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B and mish metals, and a total content of the elements is 0.1% or less in mass percent. 
     
     
       6. The copper alloy having excellent stress relaxation properties according to  claim 2 , wherein the copper alloy further comprises at least one element selected from the group consisting of Hf, Th, Li, Na, K, Sr, Pd, W, S, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B and mish metals, and a total content of the elements is 0.1% or less in mass percent. 
     
     
       7. The copper alloy having excellent stress relaxation properties according to  claim 3 , wherein the copper alloy further comprises at least one element selected from the group consisting of Hf, Th, Li, Na, K, Sr, Pd, W, S, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B and mish metals, and a total content of the elements is 0.1% or less in mass percent. 
     
     
       8. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy has a conductivity of 31 to 41% IACS. 
     
     
       9. The copper alloy having excellent stress relaxation properties according to  claim 2 , wherein the copper alloy has a conductivity of 31 to 41% IACS. 
     
     
       10. The copper alloy having excellent stress relaxation properties according to  claim 3 , wherein the copper alloy has a conductivity of 31 to 41% IACS. 
     
     
       11. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy has a yield strength of about 480 MPa or more. 
     
     
       12. The copper alloy having excellent stress relaxation properties according to  claim 2 , wherein the copper alloy has a yield strength of about 480 MPa or more. 
     
     
       13. The copper alloy having excellent stress relaxation properties according to  claim 3 , wherein the copper alloy has a yield strength of about 480 MPa or more. 
     
     
       14. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy comprises 0.3 to 2.0% Ni. 
     
     
       15. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy comprises 0.3 to 2.0% Sn. 
     
     
       16. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy comprises 0.04 to 0.2% P. 
     
     
       17. The copper alloy having excellent stress relaxation properties according to  claim 1 , wherein the copper alloy comprises 0.3 to 2.0% Ni, 0.3 to 2.0% Sn, and 0.04 to 0.2% P. 
     
     
       18. A copper alloy having excellent stress relaxation properties comprising:
 0.1 to 3.0% of Ni, 
 0.1 to 3.0% of Sn, and 
 0.01 to 0.3% of P, 
 
       in mass percent respectively, and the remainder being copper and inevitable impurities,
 wherein the Ni/P ratio in the copper alloy is from 10.2 to 17.5; 
 wherein in a radial distribution function around a Ni atom according to a XAFS analysis method, a first peak position is within a range of 2.16 to 2.35 Å, the position indicating a distance between a Ni atom in Cu and an atom nearest to the Ni atom; 
 wherein said copper alloy has a conductivity of 24 to 41 MACS; 
 wherein said excellent stress relaxation properties are defined as having a stress relaxation ratio of 11 to 15% in the direction perpendicular to the direction the copper alloy is rolled; and 
 wherein said copper alloy is made by a method which comprises:
 (1) final cold rolling wherein the range of the draft in final cold rolling is 30 to 70%; and 
 (2) low-temperature annealing in a continuous annealing furnace at a substance temperature of 300 to 500° C. after final cold rolling, with a heating rate of low-temperature annealing in the continuous annealing furnace of 50° C./sec or more and a cooling rate after low-temperature annealing in the continuous annealing furnace of 100° C./sec or more.